1. Field of the Invention
The present invention relates to an optical disk apparatus that reads data from an optical disk such as DVD or CD, and records data in the optical disk.
2. Description of the Related Art
The optical disk apparatus that can make the readout of data recorded in the optical disks such as DVD and CD and the recording of data has been generally widespread.
The optical disk apparatus applies the laser light of read power to the optical disk set on the main body, and reads the data recorded in this optical disk, as well known.
Also, it applies the laser light of record power that is greater than the read power, and records data in the optical disk. Further, the optical disk apparatus performs a tracking servo control for aligning the position where the laser light is applied to the center of the track of the optical disk of the position at the time of readout and recording and a focus servo control for aligning the focused position of laser light on a record face of the optical disk. The tracking servo control is servo control that uses a tracking error signal indicating a deflection between the position where the laser light is irradiated and the center of the track of the optical disk, and the focus servo control is servo control that uses a focus error signal indicating a deflection between the position where the laser light is focused and the record face of the optical disk. The tracking error signal and the focus error signal are signals generated by using the outputs of two or more light receiving elements that detect the reflected light from the optical disk.
On the other hand, the output of the light receiving element (quantity of reflected light from the optical disk) changes greatly between the reading time and the recording time, because the power of the laser light irradiated to the optical disk at the reading time is different from that at the recording time, as mentioned above. Therefore, if the same parameters (amplification factors) are employed to generate the tracking error signal and the focus error signal when reading and recording, the servo operation becomes unstable because the amplitude of the generated tracking error signal and the focus error signal greatly change as the output of the light receiving element changes. Thus, it has been proposed that the parameters used to generate the tracking error signal and the focus error signal are changed when reading and recording to make the amplitude of the tracking error signal and the focus error signal generated when recording and when reading equal (e.g., refer to JP-A-2001-93165).
Also, it has been proposed that the parameters used to generate the tracking error signal and the focus error signal are changed according to the total sum of the outputs of two or more light receiving elements to make the amplitude of the tracking error signal and the focus error signal generated when recording and when reading equal (e.g., refer to patent JP-A-2001-266371 and JP-A-2002-260250.
Moreover, since the reflectivity is greatly different between the recorded area (area where the pit is formed) and the unrecorded area (where the pit is not formed) of the optical disk even when reading, the output of the light receiving element changes greatly. Thus, it has been proposed that, to suppress the unstable servo operation when seeking from one area of the recorded area and the unrecorded area to the other area, the parameters used to generate the tracking error signal and the focus error signal are changed depending on the recorded area and the unrecorded area, to make the amplitude of the tracking error signal and the focus error signal generated in the recording area and the unrecorded area equal (e.g., refer to JP-A-2003-242660).